Arc regulator



Jan. 21, H H' STRONG ARC REGULATOR Filed March 9, 1934 HARRY H- TRoNG.

I NvLNToK ATTORNLT A v .az .f4

Patented Jan. 21, 1936 UNITED STATES PATENT OFFICE Application March 9,

, 12 Claims.

This invention relates to arc regulators, particularly adapted for eiecting and regulating the ieed of the electrodes of the arc of a motion picture projector, and the principal object of my invention is to provide a new and improved arc regulator of this character.

In the drawing accompanying this speciiication, and forming part of this application, I have shown, for purposes of illustration, one form which my invention may assume, and in this drawing: Y

Figure l is a view illustrating the motor employed to feed the electrodes, and showingalso the connections of the motor into the circuit, While FigureZ is a diagrammatic view showing the electrical arrangement of all of the parts.

Figure 3 is a diagrammatic view showing a conventional way in which the motor may be mechanically connected tothe electrodes.

The embodiment of the invention herein disclosed comprises an arc l2 having electrodes l0 and I I advanced and retracted through any suitable mechanism (not shown) by means of an electric motor I3 provided with a frame I rotatably supporting an armature l5 provided with a commutator I6 contacted by brushes Il and i8 respectively Vcarried by brush holders I9 and 20 supported by the motor frame I 4, as shown.

`The motor frame I4 also supports a pair of field poles 2l and 22, the pole 2I having a first eld coil 23 arranged to set up a magnetic flux in one direction, and the pole 22 having an opposing eld coil 24, arranged to set up a magnetic iiux in the reverse direction.

The embodiment of my invention herein shown is designed for use with either direct or alternating current, and includes three parallel circuits between the line wires 30 and 3|. A iirst' circuit, herein designated as the armature circuit, consists of a connecting conductor 4l), the brush I1, the armature I5, the brush I8, and a connecting conductor 4I. A second circuit, herein designated as the potential circuit, consists of a connecting conductor 36, the potential field coil 23, a connecting conductor 31, a variable resistor 39, and a connecting conductor 42. The third circuit, herein identified as the current circuit, consists of a connecting conductor 32, the current eld coil 24, a connecting conductor 34, the arc I2, and a connecting conductor 35.

With these connections it will be obvious that the current field coil 24 is connected in series with the arc I2, so that the current eld will be proportional to the current flowing through the arc I2, and that the potential eld coil 23 is connected across the arc I2, so that the potential field will be proportional to the voltage drop across the arc I2. It is well known, of course, that as the electrodes l0 and II separate, the voltage 1934, Serial No. 714,818

drop across thearc I2 increases, and the current decreases, and that the reverse occurs when the electrodes I 0 and II approach each other, and accordingly it will readily be understood that with the proper adjustment in strength between 5 the potential iield coil 23 and the current field coil 24, the decrease in current and increase in voltage drop, as the electrodes I0 and II separate, will cause the potential field coil 23 to predominate over the current leld coil 24, and the resultant field to be in one direction, while the increase in current, and the decrease in voltage drop, as the electrodes I0 and II approach each other, will cause the current iield coil 24 to predominate over the potential field coil 23, and the resultant l5 eld to be in the reverse direction.

Inasmuch as the armature is always energized in the same way, the change in direction of the resultant iield will obviously change the direction of rotation of the armature I5, and accordingly, with the proper connections between the motor and the electrode feeding mechanism, the predominance of the potential iield coil 23, when the electrodes separate too far, will cause the armature I5 to rotate to advance the electrodes i0 and. I I, andthe predominance of the current field coil 24, as the electrodes approach too closely, will cause the armature I5 to rotate in the reverse direction, to separate the electrodes.

Under normal motor conditions, however, the 30 speed of rotation of the motor armature varies inversely as the strength of the field, and accordingly, with normal motor conditions, the armature I5 would rotate with increasing speed as the electrodes approach the proper spacing 35 and the resultant eld aproaches zero, and then would tend to rotate at maximum speed the reverse direction, as soon as the resultant eld had changed polarity. In order to eliminate this undesirable action I form the circuit of the ar- 40 mature-I5 of such high resistance that the impedance drop is substantially equal to the entire line-voltage, and the counter-electro-motiveforce drop across the armature I5 is negligible, at substantially all speeds at which the armature 45 rotates, so that the current ilowing through the armature circuit is substantially unaffected by change in counter-electro-motive-force, and remains substantially constant, at all times. Under these conditions the tendency of the armature I5 50 `to speed up in response to resultant eld weakening is substantially eliminated, and further, because of the constant current in the armature I5, the armature I5 actually operates faster upon increase in resultant iield strength, because of 55 the increase in torque resulting from the fact that with the current substantially constant in the armature I5, the torque is directly proportional to the iield strength.

I accordingly produce a condition wherein the motor speed decreases with decrease in field strength through a zero speed at the point of zero iield strength, and then increases in speed in the reverse direction as the resultant field increases in strength also in the reverse direction.

Obviously, with the parts properly proportioned, the potential eld and the current eld will exactly balance at that point at which the electrodes are properlyspaced to secure the desired arc, and the armature I5 will maintain the electrodes so spaced. However, variation in operating conditions may unbalance the two fields,

and in order to compensate for this action I formv the resistor 39 variable, to provide for adjustment.

I have found that placing the potential field coil 23 and the current eld coil 24 on the separate pole pieces 2l and 22, on opposite sides of the armature I5, provides a motor that operates satisfactorily on either direct or alternating current.

In some instances it may be desirable to include in the motor dead poles 43 intermediate the active poles 2l and 22.

Under these circumstances I attribute the successful operation on alternating current tothe provision of a construction reducing mutual induction between the potential iield coil 23 and the current field coil 24.

It seems that inductive reactance between the two elds tends to delay change in predominance of the elds, and that the placing oi the two coils on the separate poles reduces this reactance below the amount effective to cause objectionable delay. It seems that not more than approximately three-fourths of the flux of either eld should react inductively with the winding of the other iield.v

However, my invention is not to be taken as 'limited by or to any theory or explanation, nor

to any particular means or use; on the contrary, while it will be obvious to those skilled in the art that the embodiment of the invention herein disclosed accomplishes the principal object of the invention, it also will be obvious that my invention is adapted for uses and purposes not herein particularly referred to, and that the embodiment thereof may be variously changed and modified, without departing from the spirit of my invention, and accordingly, it will be understood that the embodiment herein disclosed is illustrative only, and that my invention is not limited thereto.

I claim:

1. An electric motor, including: an armature; a single stator-core for coacting with said armature; a winding for said stator-core, said winding when energized tending to produce a flux in said stator-core effective to turn said armature in one direction; another winding for said stator-core, said winding when energized tending to produce a iiux in said stator-core effective to turn said armature in the opposite direction while said rst named winding is energized; said armature responding to the resultant flux in said stator-core; said windings being disposed on -said stator-core in spaced relation so as to promote leakage of flux between said windings.

2. An electric motor, including: an armature; a single stator-core for coacting with said armature; a winding for said stator-core, said winding when energized tending to produce a flux in said stator-core effective tov turn said arma- Iture in one direction; another winding for Said stator-core, said winding when energizedtending .to produce a flux in said stator-core eiective to turn said armature in the opposite direction while said first named winding is energized;` said armature responding to the resultant ux in said stator-core; said windings being disposed on said stator-core in spaced relation, the relation between said windings and core being such that the ux leakage between said windings is approximately one-fourth of the iiux of the respective windings.

3. An electric motor, including: a single stator-core having a pair of poles; an armature coacting with said poles; a differential field winding for said poles, said winding comprising two components, one of said components being disposed preponderatingly on one pole of said pair of poles and the other of said components being disposed preponderatingly on the other pole of said pair of poles; and connection means for said winding whereby said components may be simultaneously energized and whereby one of said components is adapted to coact with said armaturer in a. sense opposite from said other component.

4. An electric motor, including: a single stator-core having a pair of poles; a differential eldvwinding for said poles, said winding comprising two components, one of said components being disposed preponderatingly on one pole of said pair of poles and the other of said components being disposed preponderatingly on the other pole of said pair of poles; a pair of windingless interpoles alternated with the poles carrying said components; an armature coacting with said poles and interpoles; and connection means for said windingfwhereby said components may be simultaneouslyl energized and whereby one of said components is adapted to coact with said armature in a sense opposite from said other component.

5. An electric motor, including: an armature; a single stator-core for coacting ith said armature; a winding for said stator-core, said winding when energized tending to produce a fluxin said stator-core eiective to turn said armature in one direction; another winding for said stator-core, said winding when energized tending to produce a flux in said stator-core eiective to turn said armature in the opposite direction;

' means for energizing said windings simultaneously whereby said armature turns in a direction dependent upon the predominance of one of said windings over the other; said windings being disposed on said stator-core in spaced relation so that relative changes in the energizations of said windings causes substantially contemporaneous changes, in said predominance, substantially proportionate to said relative changes in energizations.y

6. An alternating current electric motor, including: an armature; a single stator-core for coacting with said armature; a winding for said stator-core, said winding when energized tending to produce an alternating iiux in said stator-core eiective to turn said armature in one direction; another winding for said stator-core, said winding when energized tending to produce an alternating flux in said stator-core effective to turn said armature in the opposite direction; means for energizing said windings simultaneously whereby said armature turns in a direction dependent upon the predominance of one of said windings over the other; said windings being disposed on said stator-core in spaced relation so a movable element the position of which iniluences the current through said device and the :potential drop around said device; means for maintaining constant the relation between the current through said device and the potential drop around said device, comprising, an electric motor drivingly connected to said movable element, said motor having an armature and a single stator-core for coacting with said armature; a winding for said stator-core, in series with said device, said winding when energized tending to produce a ux in said stator-core eifective to turn said armature in one direction;

another winding for said stator-core, in shunt with s'aid device, said winding when energized tending to produce a flux in said stator-core eiective to turn said armature in the opposite direction while said iirst named winding is energized; said armature responding to the resultant ilux in said stator-core; said windings being disposed on said stator-core in spaced relation so as to promote leakage of iiux between said windings.

8. In combination: an electrical device having a movable element the position oi' which iniluences the current through said device and the potential drop around said device; means for maintaining constant the relation between the current through said device and the potential drop around said device, comprising, an electric motor drivingly connected to said movable element, said motor having a single stator-core having a pair of poles and an armature coacting with said poles, a diierential field winding for said poles, said winding comprising two components, one of said components being disposed l preponderatingly on one pole of said pair of poles and the other oi.' said components being disposed preponderatingly on the other pole of said pair of poles, one of said components being connected in series with said device and the other in shunt with said device.

9; In combination: an electrical device having a movable element the position ci which influences the current through said device and the potential drop around said device; means for maintaining constant the relation between the current through said device and the potential drop around said device, comprising, an electric motor drivingly connected to said movable element, said motor having a single stator-core having a pair of poles, a diierential field winding for said poles, said winding comprising two components, one of said components being disposed preponderatingly on one pole oi said pair of poles and the other of said components being disposed preponderatingly on the other pole of said pair of poles, one of said components being connected in series with said device and the other in shunt with said device, said motor having a pair of maintaining constant the relation between thev current through said device and the potential drop around said device, comprising, an electric motor drivingly connected to said movable element, said motor having an armature and a single stator-core for coacting with said armature; a winding for said stator-core, in series with said device, said winding when energized tending to produce a flux in said stator-core eiective to turn said armature in one direction; another winding for said stator-core, in shunt with said device, said winding when energized tending to produce a ux in said stator-core effective to turn sani armature in the opposite direction; means for energizing said winding simultaneously whereby said armature turns in a direction dependent upon the predominance of one of said windings over the other; said windings being disposed on said stator-core in spaced relation so that relative changes in the energizations of said windings causes substantially contemporaneous changes, in said predominance, substantially proportionate to said relative changes in energizations.

ll. In combination: an alternating current electrical device having a movable element the position of which influences the current through said device and the potential drop around said device; means for maintaining constant the relation between the current through said device and the potential drop around said device, comprising, an alternating current electric motor drivingly connected to said movable element, said motor having an armature and a single statorcore for coacting with said armature; a winding for said stator-core, in series with said device, said winding when energized tending to produce a flux in said stator-core eiective to turn said armature'in one direction; another winding for said stator-core, in shunt with said device, said winding when energized tending to produce a flux in said stator-core effective to turn said armature in the opposite direction; means for energizing said windings simultaneously whereby said armature turns in a direction dependent upon the predominance of one of said windings over the other; said windings being disposed on said stator-core in spaced relation so that relative changes in the energizations of said windings causes changes in said predominance substantially proportionate to said relative changes in energizations.

12. In combination: an electrical device having a movable element the position voi! which inuences the current through said device and the potential drop around said device; means for maintaining constant the relation between the current through said device and the potential drop around said device, comprising, an electric motor drivingly connected to said movable element, said motor having a single stator-core having a pair of poles and an armature coacting with said poles, said armature being-connected in shunt with said device, a di'erential field winding for said poles, said winding comprising twocomponents, one of saicl components being disposed preponderatingly on one pole of said pair oi poles and the other of said components being disposed preponderatingly on the other pole of said pair of poles, one of said components being connected in series with said device and the other in shunt with said device. 

